Interactions between freshwater snails and tadpoles: competition and facilitation

Summary Freshwater snails and anuran tadpoles have been suggested to have their highest population densities in ponds of intermediate size where abiotic disturbance (e.g. desiccation) is low and large predators absent. Both snails and tadpoles feed on periphytic algae and, thus, there should be a large potential for competitive interactions to occur between these two distantly related taxa. In a field experiment we examined the relative strength of competition between two closely related snail species, Lymnaea stagnalis and L. peregra, and between L. stagnalis and tadpoles of the common frog, Rana temporaria. Snail growth and egg production and tadpole size at and time to metamorphosis were determined. Effects on the common food source, periphyton, were monitored with the aid of artificial substrates. Periphyton dry weight was dramatically reduced in the presence of snails and/or tadpoles. There were no competitive effects on growth or egg production of the two snail species when they were coexisting. Mortality of L. peregra was high (95%) after reproduction, but independent of treatment. Growth of L. stagnalis was reduced only at the highest tadpole densities, whereas egg production was reduced both by intraspecific competition and by competition with tadpoles. Differences in egg production were retained after tadpole metamorphosis. Tadpole larval period increased, weight of metamorphosing frogs decreased and growth rate was reduced as a function of increasing tadpole density. However, contrary to expectation, snails had a positive effect on tadpole larval period, weight and growth rate. Further, in experimental containers without snails there was a dense growth of the filamentous green alga Cladophora sp. We suggest that the facilitative effects of snails on tadpoles are due to an indirect mutualistic mechanism, involving competition between food sources of different quality (microalgae and Cladophora sp.) and tadpoles being competitively dominant over snails for the preferred food source (microalgae). In the presence of tadpoles snails will be forced to feed on low-quality Cladophora, increasing nutrient turnover rates, which results in enhanced productivity of microalgae, increasing tadpole food resources. Thus, tadpoles have a negative effect on snails through resource depression, while snails facilitate tadpole growth through an indirect enhancement of food availability.     

Seasonal distribution of the invasive snail, <Emphasis Type="Italic">Bithynia tentaculata,</Emphasis> within infested waterbodies in Minnesota,USA, including waterfowl migration

The introduction of the invasive faucet snail (Bithynia tentaculata) and its associated trematodes, Cyathocotyle bushiensis, Sphaeridiotrema spp., and Leyogonimus polyoon, has resulted in recurring waterfowl die-offs during spring and fall migration in the Great Lakes Region, especially of Lesser scaup (Aythya affinis) and American coots (Fulica americana). Here we evaluated faucet snail habitat use and abundance in infested waterbodies in northcentral Minnesota (USA) during spring, summer, and fall of 2011–2013. We collected snail samples, along with data on abiotic and biotic variables, at 12 snail-infested waterbodies. We used Generalized Estimating Equations to develop models that explain variability in the distribution and abundance of snails within waterbodies. Models containing water depth consistently received considerable support in waterbodies where depth varied substantially; however the specific shape of these relationships varied among waterbodies. Snails used a wide range of depths, but were more likely to be present in deep portions (~6 m) of large lakes in all seasons. We found seasonal differences in the location of rafts of migrating scaup, with use of areas closer to shore in the spring, and use of areas shallower than those used most by faucet snails. Patterns in snail distribution likely influenced the availability of snails for consumption by migrating waterfowl; differences in portions of large lakes used by migratory waterfowl as stopover sites and by faucet snails may reduce exposure of migrating waterfowl to trematodes in infested lakes. However, some spatio-temporal overlap between snails and scaup occurs and explains the continuing loss of waterfowl to trematodiasis.     

Effects of temperature and food quality on isotopic turnover and discrimination in a cladoceran

Our experimental study was designed to assess the effects of temperature on nitrogen isotope turnover and to measure the effects of temperature and food quality on the stable carbon and nitrogen isotope discrimination factors (Δ¹³C and Δ¹⁵N) in a cladoceran. For the first part of our study, Daphnia were fed with non-enriched or ¹⁵N-enriched Scenedesmus obliquus at 12, 15, 20, and 25 °C. For the second part, Daphnia were reared at 15, 20, and 25 °C on Scenedesmus or Cryptomonas sp. There were no clear effects of temperature on turnover rates of the nitrogen isotope of cladocerans. However, a general increase in Δ¹³C with increasing temperature was measured, regardless of the food source. Δ¹⁵N was also affected by temperature, but contrasting results were measured depending on the food source used. There were significant effects of food quality on Δ¹³C and Δ¹⁵N in Daphnia, as values obtained for Daphnia fed Scenedesmus were always higher than those obtained for Daphnia fed Cryptomonas. Our experiments produced discrimination factors that were very different from those usually considered in isotope studies and showed that the values used for isotope model implementation to analyze field data need to be adapted to environmental conditions.     

Associations Between Macroinvertebrates and <Emphasis Type="Italic">Paralemanea mexicana</Emphasis>, an Endemic Freshwater Red Alga from a Mountain River in Central Mexico

Macrophytes are common inhabitants of lotic environments and, depending on their morphological traits, possess adaptations that provide shelter to aquatic invertebrates against strong river flow and predators. They may also be used as a food source by macroinvertebrates. The main goal of this study was to determine the relationship between the red alga Paralemanea mexicana and its role as a shelter and/or food source for lotic macroinvertebrates. We also conducted research on the role of microhabitat and morphological variations of the alga in determining macroinvertebrate taxon abundance, diversity, and functional group composition in a high-current velocity river. Results showed that changes in cover and morphology of P. mexicana were mostly correlated with river current velocity, irradiance, and seasonal variation. In turn, these were related to changes in abundance and diversity of the associated macroinvertebrate community. In addition, six macroinvertebrate functional feeding groups were evaluated for associations with the red alga: filtering and gathering collectors, piercers, scrapers, herbivore shredders, and predators. The results showed that the Trichoptera Hydroptilidae genera Ochrotrichia and Metrichia use P. mexicana as a food source and case-building material. The Trichoptera Glossosomatidae Mortoniella uses the alga as a substrate. The biotic interactions between P. mexicana and associated macroinvertebrates reveal the importance of macrophytes as purveyors of substrate, as food and shelter for macroinvertebrates, and also as promoters of macroinvertebrate community diversity. In addition, it was shown that macroinvertebrate herbivory likely facilitates vegetative propagation of the red alga through increased release and germination of carpospores and new gametophytes.     

The osphradium is involved in the control of egg-laying in the pond snail Lymnaea stagnalis

Summary

Ablation of the osphradium (a peripheral putative chemo-sensory organ) in Lymnaea stagnalis resulted in significant increase of egg-laying activity as compared with control animals (observed for 50 days). Cutting the osphradial nerve increased egg-laying to a lesser degree and only for the first 15–20 days. Water changes in the aquaria had a similar stimulating effect on egg-laying activity in both osphradium-deprived and control snails. Permanent aeration of the aquaria abolished this effect. Possible mechanisms of tonic inhibitory action of the osphradium on egg-laying are discussed.     

Seasonal variation in nutritional composition and anti-proliferative activity of brown seaweed, <Emphasis Type="Italic">Sargassum oligocystum</Emphasis>

This study investigated the nutritional components and anti-proliferative activity of Sargassum oligocystum against an adriamycin-resistant human small cell lung carcinoma cell line (GLC4/Adr). The seaweed samples were collected from Nang Rong Beach, Chonburi Province, Thailand in February (the hot/dry season), May (the early monsoon season), August (the monsoon season) and December (the cool/dry season) of 2012. In general, the nutritional composition of S. oligocystum was high during the hot dry and early monsoon season. Additionally, four different types of extract were obtained: ethanolic extract (E1), lipophilic extract (E2), acidic extract (E3) and alkali extract (E4). The highest anti-proliferative activity was found in samples collected during the monsoon season. It is noteworthy that the E2 extract collected during the monsoon season was the most effective, with an IC₅₀ (half maximal inhibitory concentration) value of 2.52 ± 0.54 μg mL^?1. The anti-proliferative activity showed a positive correlation with vitamin E (α-tocopherol) in the extracts. However, there were no clear correlations between the total phenolic or fucoxanthin contents and anti-proliferative activity. These results indicate that S. oligocystum has potential as an alternative source for functional food or cancer treatments in the future.     

Rhabditis maupasi: occurrence in food snails and cultivation

Rhabditis maupasi, a nematode, inhabits the mantle cavity of terrestrial snails, Helix aspersa, that are imported from Morocco and sold in the food markets of New York City. Most of the nematodes found in living snails are stage-3 larvae which mature and reproduce after the snail has died and decayed. The nematodes were isolated from snails and cultivated with a microflora and then in species isolation, i.e., axenically. Sterile slices of rabbit kidney supported by agar slants served as the initial culture system. Subsequently, a liquid medium was used that contained raw rabbit liver extract. When, instead, raw snail extract was substituted in the liquid medium, nematode larvae did not mature unless the snail extract was digested secondarily or inactivated by heating. Nematodes grow abundantly in dead snails and in treated snail extract but not in living snails or in raw snail extract. The reason is probably not the nematodes' lack of suitable digestive enzymes for snail tissue nor the absence of adequate nutrients in living, microbially poor snails, but rather the presence of an inhibitor in snails.     

Detection and Enumeration of Clostridium difficile Spores in Retail Beef and Pork

Recent studies have identified Clostridium difficile in food animals and retail meat, and concern has been raised about the potential for food to act as a source of C. difficile infection in humans. Previous studies of retail meat have relied on enrichment culture alone, thereby preventing any assessment of the level of contamination in meat. This study evaluated the prevalence of C. difficile contamination of retail ground beef and ground pork in Canada. Ground beef and ground pork were purchased from retail outlets in four Canadian provinces. Quantitative and enrichment culture was performed. Clostridium difficile was isolated from 28/230 (12%) samples overall: 14/115 (12%) ground beef samples and 14/115 (12%) ground pork samples (P = 1.0). For ground beef, 10/14 samples (71%) were positive by enrichment culture only. Of the 4 ground beef samples that were positive by direct culture, 20 spores/g were present in 2 while 120 and 240 spores/g were present in 1 each. For ground pork, 10/14 (71%) samples were positive by enrichment culture only. Of the 4 ground pork samples that were positive by direct culture, 20 spores/g were present in 3 while 60 spores/g were present in 1. Ribotype 078 predominated, consistent with some previous studies of C. difficile in food animals. Ribotype 027/North American pulsotype 1 was also identified in both retail beef and pork. This study has identified relatively common contamination of retail ground beef and pork with C. difficile spores; however, the levels of contamination were very low.Clostridium difficile is an important cause of enteric disease in humans. It is the most commonly diagnosed cause of hospital- and antimicrobial agent-associated diarrhea in people, and recent evidence suggests that it may be emerging as an important community-associated pathogen (2, 5). In addition to humans, C. difficile can be found in the intestinal tracts of a variety of animal species, including food animals, such as cattle and pigs (7, 10, 13). Clostridium difficile has also been found in retail meat (11, 12, 17), and concerns about the role of food in the epidemiology of community-associated C. difficile infection (CA-CDI) have been expressed (5, 8, 15).Initial studies have reported isolation of C. difficile from 4.6 to 45% of retail meat samples (11, 12, 17). However, all studies have used broth enrichment protocols, which could detect very low spore numbers and provide no information about the number of organisms present in a sample. No studies have evaluated numbers of C. difficile spores in food. While the infectious dose is not known, an understanding of the level of contamination may be an important factor in determining the relevance of contamination of food. Additionally, the use of different methods between studies hampers comparison of results. Recently a study was performed to evaluate different methods for qualitative and quantitative detection of C. difficile (21). This study determined that the detection threshold of enrichment culture could be at least as low as 10 spores/g of meat. It also determined that quantitative culture can accurately determine the level of contamination in experimentally inoculated meat samples, albeit with a higher detection threshold. The objective of this study was to determine the prevalence of C. difficile contamination of retail ground beef and ground pork using both qualitative and quantitative methods.     

Incorporation of Exotic Spartina alterniflora into Diet of Deposit-Feeding Snails in the Yangtze River Estuary Salt Marsh: Stable Isotope and Fatty Acid Analyses

The response of deposit-feeding animals to plant invasions is still unclear, because their food sources are often difficult to identify. We examined the effect of the exotic plant species, Spartina alterniflora, on the food source composition of two dominant snail species, Assiminea latericea and Cerithidea largillierti, in the Yangtze River estuary salt marsh using a combination of stable isotope and fatty acid analyses. We collected the snails and their potential food materials (sediment organic matter, particulate organic matter, and plant material) in S. alterniflora and native plant Phragmites australis marshes and then determined the composition of food sources of snails based on fatty acid markers and stable isotope composition. Our results indicated that A. latericea and C. largillierti are deposit feeders grazing on sedimentary particles originating from diatoms, bacteria, and vascular plants. Invasive S. alterniflora did not result in a change in the relative contribution of microalgae, bacteria, and vascular plants to the food source of the snails. Spartina alterniflora was confirmed to be assimilated by both snail species. The higher assimilation of S. alterniflora by A. latericea compared with C. largillierti is probably related to the greater ability of A. latericea to assimilate plant materials from detritus, as evidenced by fatty acid composition. Overall, S. alterniflora can be incorporated into the food web of the estuarine salt marsh by the dominant snail species with generalist-feeding habits.     

Consequences of food-attraction conditioning in Helix: a behavioral and electrophysiological study

Food-attraction conditioning is a learning phenomenon by which adult Helix pomatia acquire the ability to locate food through exposure to that particular food. Food-conditioned snails can be distinguished from naive snails during their approach to food. Naive snails keep their tentacles upright — whereas food-conditioned animals bend the tentacles down-ward, in a horizontal orientation, pointed in the direction of the food.Tentacle musculature is innervated by two peritentacular nerves (PTn), each projecting to approximately one hemi-section of the tentacle wall. Stimulating the peritentacular nerves caused the tentacles to bend downward in a manner reflecting the full complement of tentacle movements performed by conditioned snails.The neural correlate of tentacle movements was investigated in isolated ganglion preparations with the posterior tentacles attached. PT nerve activity was recorded while the olfactory epithelia were stimulated with natural food odors. Preparations obtained from conditioned animals responded with a substantial increase in unit activity (mean increase 280%) to stimulation with odor of the conditioned food but not to other odors. Preparations from naive animals did not respond to food odor stimulation. The electrophysiological results demonstrated that plasticity due to conditioning the snails in vivo survived dissection and could be monitored in vitro.Abbreviations ext PTn external peritentacular nerve - int PTn internal peritentacular nerve     

The sugar chemoreception niches of Bulinus (physopsis) globosus (morelet) and Bulinus rohlfsi (clessin), the two most important snail hosts of Schistosoma haematobium (Bilharz) in West Africa

• 1.1.The behavioural responses of two species of freshwater pulmonate snails Bulinus (P.) globosus and Bulinus rohlfsi] to sugar gradients were investigated by means of diffusion olfactometers.
• 2.2.Both snail species proved to be very discriminating in their responses. Of the 17 sugars tested, 35.3%, namely d(−)glucuronic, maltotriose, maltose, cellobiose, d(−)arabinose, d(+)mannose proved to be statistically significant attractants or arrestants to B. rohlfsi. Only 23.5% of these sugars (maltotriose, maltose), d(+) mannose and d(+) xylose were significant attraetants or arrestants to B. (P.) globosus.
• 3.3.Glucuronic acid was a significant repellent to B. rohlfsi but none of the sugars was a repellent to B. (P.) globosus.
• 4.4.The results are compared with those obtained for other snail species and their relevance to the ecology and control of the snails are discussed.

     

Foraging strategy switch in detour behavior of the land snail Anguispira alternata (Say)

Abstract. The ability of an olfactory-dominant organism, the land snail Anguispira alternata , to negotiate an odor-permeable barrier to obtain food in still air was tested. Thirty-nine snails were challenged with a "V"-shaped wire mesh fence that allowed them to get within 1 cm of their food but required them to turn away from the food to move around the fence. Fifteen snails were tested under the same conditions but without a food odor source present. Of the 39 snails tested with food, 22 moved up the odor gradient directly toward the food. Twentyone of these snails altered their foraging behavior by moving away from the odor source after they encountered the barrier. Twelve of these 21 moved along the fence to the food. The other 9 snails moved away from the fence and wandered about within the arena. Of the 39 snails tested, 17 did not move toward the food but by-passed the fence by either following the arena edge or moving toward the gap between the fence and the arena wall. Since some of these snails obtained the food without encountering the fence, a second experiment challenged 19 snails with a "J"-shaped fence in which one of the possible detour paths was blocked. There was no difference in the number of snails taking the blocked path vs. snails taking the open path. Therefore it is unlikely that these snails were able to detect the fence and plot a path around it before actually moving. In the 2 experiments, 91% of the snails that followed the odor gradient directly toward the food subsequently switched their foraging behavior. The ability of these snails to switch their foraging behavior was unexpected in an olfactory-dominant animal and suggests that their behavior is based on a significant amount of sensory processing.     

Functional changes in the snail statocyst system elicited by microgravity

Background

The mollusk statocyst is a mechanosensing organ detecting the animal''s orientation with respect to gravity. This system has clear similarities to its vertebrate counterparts: a weight-lending mass, an epithelial layer containing small supporting cells and the large sensory hair cells, and an output eliciting compensatory body reflexes to perturbations.

Methodology/Principal Findings

In terrestrial gastropod snail we studied the impact of 16- (Foton M-2) and 12-day (Foton M-3) exposure to microgravity in unmanned orbital missions on: (i) the whole animal behavior (Helix lucorum L.), (ii) the statoreceptor responses to tilt in an isolated neural preparation (Helix lucorum L.), and (iii) the differential expression of the Helix pedal peptide (HPep) and the tetrapeptide FMRFamide genes in neural structures (Helix aspersa L.). Experiments were performed 13–42 hours after return to Earth. Latency of body re-orientation to sudden 90° head-down pitch was significantly reduced in postflight snails indicating an enhanced negative gravitaxis response. Statoreceptor responses to tilt in postflight snails were independent of motion direction, in contrast to a directional preference observed in control animals. Positive relation between tilt velocity and firing rate was observed in both control and postflight snails, but the response magnitude was significantly larger in postflight snails indicating an enhanced sensitivity to acceleration. A significant increase in mRNA expression of the gene encoding HPep, a peptide linked to ciliary beating, in statoreceptors was observed in postflight snails; no differential expression of the gene encoding FMRFamide, a possible neurotransmission modulator, was observed.

Conclusions/Significance

Upregulation of statocyst function in snails following microgravity exposure parallels that observed in vertebrates suggesting fundamental principles underlie gravi-sensing and the organism''s ability to adapt to gravity changes. This simple animal model offers the possibility to describe general subcellular mechanisms of nervous system''s response to conditions on Earth and in space.     

Field observations on the influence of low water velocities on drifting of Bulinus globosus

The influence of water velocities of less than 30 cm/s on drifting of Bulinus globosus in a natural stream was investigated. It is shown that although a low water velocity does not sweep away adhering snails, it carries away snails releasing their hold and crawling along the water surface in search of new food sources. A low water velocity therefore assists considerably to the spreading of a snail species. Vegetation was found to have a decisive impact on local water velocity conditions by reducing the current and creating protected pockets. Upstream migration was found not to be common among Bulinus globosus. In addition, evidence for snail drifting under natural conditions within well established Schistosoma haematobium transmission sites is presented.     

Nutraceutical effects of table green olives: a pilot study with <Emphasis Type="Italic">Nocellara del Belice</Emphasis> olives

Background

The aim of this study was to analyse the nutraceutical properties of table green olives Nocellara del Belice, a traditional Mediterranean food. The Mediterranean Diet has as key elements olives and extra virgin olive oil, common to all Mediterranean countries. Olive oil is the main source of fat and can modulate oxidative stress and inflammation, whereas little is known about the role of olives. Moreover, emerging evidences underline the association between gut microbiota and food as the basis of many phenomena that affect health and delay or avoid the onset of some age-related chronic diseases.

Methods

In order to show if table green olives have nutraceutical properties and/or probiotic effect, we performed a nutritional intervention, administering to 25 healthy subjects (mean age 38,3), 12 table green olives/day for 30 days. We carried out anthropometric, biochemical, oxidative stress and cytokines analyses at the beginning of the study and at the end. Moreover, we also collected fecal samples to investigate about the possible variation of concentration of Lactobacilli, after the olives consumption.

Result

Our results showed a significant variation of one molecule related to oxidative stress, malondialdehyde, confirming that Nocellara del Belice green olives could have an anti-oxidant effect. In addition, the level of interleukin-6 decreased significantly, demonstrating how this food could be able to modulate the inflammatory response. Moreover, it is noteworthy the reduction of fat mass with an increase of muscle mass, suggesting a possible effect on long time assumption of table olives on body mass variation. No statistically significant differences were observed in the amount of Lactobacilli, although a trend towards an increased concentration of them at the end of the intervention could be related to the nutraceutical effects of olives.

Conclusion

These preliminary results suggest a possible nutraceutical effect of daily consumption of green table olives Nocellara del Belice. To best of our knowledge, this is the first study performed to assess nutraceutical properties of this food. Of course, it is necessary to verify the data in a larger sample of individuals to confirm their role as nutraceuticals.

     

Effects of an exotic bivalve mollusc on benthic invertebrates and food quality in the Ohio River

Effects of zebra mussels (Dreissena polymorpha) on populations of amphipods (Gammarus fasciatus) and prosobranch snails (Lithasia obovata) and on nutritional quality of benthic organic matter were examined in 20 artificial streams receiving Ohio River water and containing either mussels or small gravel. Twenty individually-marked snails were placed in each trough, and streams were allowed to colonize with other benthic species for 28 days.Dreissenids positively affected other benthic invertebrates in our stream channels. Compared to gravel channels, Gammarus biomass was significantly higher (P<0.01) in mussel channels, amphipod densities increased 300%, and snail growth rates were 50% greater. Food quality of fine benthic organic matter (FBOM) was greater in mussel channels (i.e. lower C:N), and FBOM was carbon depleted (lower ¹³C) but nitrogen enriched (higher ¹⁵N). Isotope data suggest that detrital FBOM was not the sole food source for snails and amphipods in our channels and that they were assimilating a higher quality portion of this BOM. The overall influence of dreissenids on particular benthic invertebrates may depend on the response and/or susceptibility of those species to biofouling, increased habitat heterogeneity, and changes in the quality and quantity of nutrients.     

Microhabitats within Venomous Cone Snails Contain Diverse Actinobacteria

Actinomycetes can be symbionts in diverse organisms, including both plants and animals. Some actinomycetes benefit their host by producing small molecule secondary metabolites; the resulting symbioses are often developmentally complex. Actinomycetes associated with three cone snails were studied. Cone snails are venomous tropical marine gastropods which have been extensively examined because of their production of peptide-based neurological toxins, but no microbiological studies have been reported on these organisms. A microhabitat approach was used in which dissected tissue from each snail was treated as an individual sample in order to explore bacteria in the tissues separately. Our results revealed a diverse, novel, and highly culturable cone snail-associated actinomycete community, with some isolates showing promising bioactivity in a neurological assay. This suggests that cone snails may represent an underexplored reservoir of novel actinomycetes of potential interest for drug discovery.Interest in natural products and drug discovery has been a major driving force for the study of microbial communities associated with marine invertebrates. Sponges, which have provided more bioactive metabolites than any other marine invertebrate group (see reference 4 and previous references in that series) have been the main focus of these investigations, yielding numerous reports of associated bacteria and complex microbial communities (17, 43). Other examples of marine invertebrate-associated microbes explored for their involvement in natural products include bryozoans (9, 41), ascidians (37), and shipworms (46). Thus far, there are literature reports of diverse bacterial taxa involved in natural product biosynthesis in marine animals (9, 10). Notably less well studied are the symbiotic actinomycetes, for which the biology of host-actinomycete associations is just beginning to be explored in a methodical way. Actinomycetes are known to be important symbionts in a number of biological systems, such as plants, insects, and marine invertebrates, contributing as nitrogen fixers in plants (39) or utilizing their chemical arsenal for defense purposes (8, 22, 38).An initial investigation of a cone snail yielded a surprisingly high number of actinomycetes (data not shown), prompting this follow-up study on additional samples. Cone snail mollusks belong to the genus Conus, which contains about 500 closely related species (11). These mollusks are well known for their complex neurologically active venoms that they use to immobilize their prey, including fish, worms, and other mollusks. The venom of cone snails has been extensively studied, but to our knowledge no study of cone snail microbial communities has been reported. Cone snails are part of the larger superfamily Conoidea, comprising ∼20,000 species, making it an extremely diverse group (25, 34). Given the initial observation of cultivable actinomycetes from cone snails, this large group seemed like a potentially excellent source of new bacterial natural products and new models of actinomycete symbiosis.The goal of this study was to examine the actinobacteria community associated with tropical marine snails of the genus Conus, using a microhabitat approach by which individual organs are treated as independent samples, and to assess the bioactivities of the isolates obtained by using a neurological assay. Although similar approaches have previously been used in microbial ecology (3, 42), this is a novel approach in drug discovery for the identification of bioactive bacteria. We report here the association between three cone snails, Conus pulicarius, Conus rolani, and Conus tribblei, and their actinobacteria as well as the bioactivities of some of these actinobacteria.     

Fast Fourier infrared spectroscopy to characterize the biochemical composition in diatoms

Diatoms are photosynthetic unicellular microalgae and are nature’s hidden source of several biosynthetic metabolites with their use in biofuel, food and drug industries. They mainly contain various lipids, sterols, isoprenoids and toxins with their use in apoptotic, fertility controlling and cancer drugs. Chemical studies on diatoms are limited due to various limitations such as variation of nutrients, contaminants and change in seasonal factors in the environment. To overcome these limitations, we obtained axenic cultures of 12 fresh-water diatom strains on the 22nd day of inoculation having a dry weight of 1 mg each and performed their Fourier transform infrared (FTIR) study for the detection of functional groups responsible for their chemical moiety. The spectral mapping showed a varied level of polyunsaturated fatty acids, amides, amines, ketone bodies and esters for their applications in various pharmacological, food and biofuel industries in the exponential phase of their growth in f/2 media. The FTIR study of the 12 diatom strains showed various similarities in the form of some common peak patterns ranging from 3000 to 3600 cm^?1 for ν_O–H absorption. The symmetric stretching vibration frequency of Diadesmis confervaceae (V2) type species showed different behaviour than others in the spectral region starting from 1600 to 1700 cm^?1. The absorption between 1500 and 1575 cm^?1 reflects the presence of the –N–H group. Infrared (IR) absorptions falling between 1600 and 1700 cm^?1 reflect the presence of amide’s ν_C=O in all species. Placoneis elginensis (V8) type species showed an additional absorption band which is centred around 1735–1750 cm^?1 which perhaps reflects the presence of ester’s ν_C=O. Diadesmis confervaceae (V2), Nitzschia palea (V4), Placoneis elginensis (V8), Nitzschia palea var. debilis (V6), Nitzschia inconspicua (V10), Gomphonema parvulum (V11) and Sellaphora (V12) showed distinct structural features with important key functionalities that can make them essential drug markers in the pharmaceutical industry.